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Thread: What's Your Fuel Consumption on MFI

  1. #1

    What's Your Fuel Consumption on MFI

    Seems like the MFI cars are always getting a bad rap for their unreasonable thirst. I have read often, on this board and others, of folks complaining about or inquiring as to the heavy thirst of these cars especially the Ss. So how about a pole of members' regular mpg. You can note how you drive to put the numbers in perspective.
    My own personal experience, stretching over 30 years of owning/driving these cars is that a well adjusted MFI will deliver very acceptable gas mileage.
    I just filled up my 73 S this morning and noted 230 miles on 10.0 gallons. 23 mpg driven mostly on fast secondary roads with several periods where the cars full potential was exploited during demo rides. This car has 68k and is stock except for J&E 95mm 9.5:1 pistons. I have averaged 25+ on some longer more sedate journeys. I'll reprot later on my 73E.
    So hows your mileage?

    Regards, Scott

  2. #2
    Mine is absolutely horrible, but I'd say my MFI is not 'well adjusted yet'. I'm betting I'm averaging ~10-12mpg. The engine goes on a Dynometer tomorrow with Dieter at the helm. I'm hoping for some improvement. The mileage on the freeway is the worst, with 70MPH using 4300RPM's. I think the low profile tires are costing me 4-5MPH on the Speedo and 5-10MPH as well.
    Chris Purpura @civilizedmisfit
    Member #479
    Current Cars:
    1972 911T aka The "Civilized Misfit" Build
    Miss February - EarlySRegistry 2023 Calendar
    1968 911S Ossi Blau/Beige Corduroy

    Past Cars:
    2019 911 Carrera GTS (sold, no regrets)
    73S - #1100 (restored and now somewhere in Europe)
    1997 993 Carrera 4S Black on Black (sold)

  3. #3
    I averaged around 20 mpg down and back to Rennsport. But there are two caveats: First, my car is Sportomatic; and second, I have not had the CO checked recently. The tailpipe is a bit on the black side.
    Thanks for starting this post. I have been curious to know what is 'normal'.
    The Capitalist Roader

  4. #4
    We are around 15-16 mpg, combined city & freeway. The mfi could use some fine tuning.

    Yopurp what gear are you in to get 70 mph @ 4300 rpm? I'm at 3400 rpm @ 70 in 5th.

    '73 S coupe
    '73 targa w3.2 (for sale)
    '74 rsr clone w/2.8 twinplug
    '68 v.w. crewcab w 2.4 & 5 speed

  5. #5
    Jared Rundell - Registered User JCR's Avatar
    Join Date
    Dec 2002
    Birmingham, MI

    I'm keepin my fingers crossed for ya! Sounds like you've got the right guy working on your MFI now.

    I'm at 15-17mpg combined, with Webers on a 2.4 (MFI waiting patiently in the closet). Mostly non freeway driving with lots of revs!
    '73 911S #0793
    '69 912_ #0602
    Early S #0454
    RGruppe #0391

  6. #6
    Some of the above figures sounded a bit low to me...then I remembered...California "reformulated fuel". When driving to Cambria '01 and back, I noticed a 10% or so mileage drop once entering California. I'm no darned if I can figure out how burning more equals less hydrocarbons in the air. Perhaps a politician could answer that?
    Paul D. Early S Registry #8 - Cyclops Minister of West Coast Affairs
    "Now, to put a water-cooled engine in the rear and to have the radiator in the front, that's not very intelligent." -Ferry Porsche (PANO, Oct. 1973)

  7. #7
    B-b-buy Bushwood?!?!
    Join Date
    Feb 2003
    Topanga Canyon, CA
    I get 9-11 mpg in daily stop n go driving around L.A.
    Probably 16-18 mpg on the freeway.
    Sandy Isaac
    '69 911E

  8. #8
    Originally posted by SandyI
    I get 9-11 mpg in daily stop n go driving around L.A.
    Probably 16-18 mpg on the freeway.

    They were never known for fuel economy. Car and Drivers' 1972 road test (February 1972) listed the fuel mileage for the T, E, S as follows:

    T - 16-20
    E - 15-18
    S - 14-17

    The article also talked about the options list available. Titanium Connecting Rods....$903.50 Ah, what heady days they were.
    BTW, the front spoiler was a $210.35 option for the T and E.

    Early S Registry #235
    rgruppe #111

  9. #9
    Oh yes those options. In '74 I was a lowly line mechanic drving my beater 356 or bicycle to work on others new 911s that I couldn't afford. I recall that the sport seat optionwas something south of $50!!
    I remember those famous road tests too. Road and Track claimed that the 2.4S they tested was slower to 60 and maybe even 100 than the 2.4E they had tested. They later allowed as how there was something amiss with the S. I can vouch for all the 2.4 Es and Ss I have driven the Ss were significantly faster if running well. Several other well respected testers and mags got better performance from the S. But, we still hear today, as if it were gospel, about how the E is faster to 60 blah blah blah.

    So... I wonder; is this how urban legends get started and stick?
    Same deal on the poor mileage. The car mags flogged the bejezzus out of the cars (who could blame them..I must confess that as a 20 year old I flogged a few customers' cars on test drives. Hell, that's how I fell in love with the 911). By their own admission R&T got an S with FI problem so it is quite conceivable that not only performance but fuel mileage was affected.

    The reason I have written this post is that I feel there is a generally accepted urban legend about MFI gas guzzling that has allowed a lot of cars to run around with poorly functioning MFI because people just say what you are saying "they were never known for fuel economy" or some such.

    My memory may be a bit dim but I don't recall owners generally complaining about poor mileage back then. And I know from my own experience that I have always gotten better mileage (even in my old 69S which I drove mecilessly in my youth) than what I see generally tossed around on this site.

    I guess I don't understand why if they are such gas pigs my 73S does comparatively well.

    Shouldn't everyone be able to duplicate the good results if the general mechanical parameters are the same?

    Is stop and go traffic that much worse where these folks live as I do think it can really screw up mileage?

    Do they just drive their cars a lot harder tham me? I live in a very rural area with NO cops, little traffic and fun roads so I doubt it.

    In this age of no maintainence cars and electronics have people forgotten or never taken the time to learn how to adjust their MFI?

    I'm just looking for answers and trying to debunk what I consider an ill deserved myth like the E vs S performance.

    Thanks for humoring me.

  10. #10
    Senior Member
    Join Date
    Jan 2003
    Mileage around 22mpg ( but Imperial not US gallons) but I drive my E like an old lady ......

    Gets to 25 on steady free way journeys....75 -80mph steady.

    A good drive in the country can see it down to low teens.

    The fewest I ever saw was sometihng like 22 litres per 100km (not sure of the mpg there) crusing at 225km/h on deserted French motorways for two and a half hours at a strectch.......

    Big fun and no tickets...

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